Cisco Systems 3750E manual Using the show platform forward Command, 45-23, Udp 10

Chapter 45 Troubleshooting

Using the show platform forward Command

Note Be aware that the debugging destination you use affects system overhead. Logging messages to the console produces very high overhead, whereas logging messages to a virtual terminal produces less overhead. Logging messages to a syslog server produces even less, and logging to an internal buffer produces the least overhead of any method.

When stack members generate a system error message, the stack master displays the error message to all stack members. The syslog resides on the stack master.

Note Make sure to save the syslog to flash memory so that the syslog is not lost if the stack master fails.

For more information about system message logging, see Chapter 32, “Configuring System Message Logging.”

Using the show platform forward Command

The output from the show platform forward privileged EXEC command provides some useful information about the forwarding results if a packet entering an interface is sent through the system. Depending upon the parameters entered about the packet, the output provides lookup table results and port maps used to calculate forwarding destinations, bitmaps, and egress information.

Note For more syntax and usage information for the show platform forward command, see the switch command reference for this release.

Most of the information in the output from the command is useful mainly for technical support personnel, who have access to detailed information about the switch application-specific integrated circuits (ASICs). However, packet forwarding information can also be helpful in troubleshooting.

This is an example of the output from the show platform forward command on port 1 in VLAN 5 when the packet entering that port is addressed to unknown MAC addresses. The packet should be flooded to all other ports in VLAN 5.

Switch# show platform forward gigabitethernet1/0/1 vlan 5 1.1.1 2.2.2 ip 13.1.1.1 13.2.2.2

udp 10 20

Global Port Number:24, Asic Number:5

Src Real Vlan Id:5, Mapped Vlan Id:5

	Ingress:
	Lookup		Key-Used			Index-Hit A-Data
	InptACL 40_0D020202_0D010101-00_40000014_000A0000					01FFA	03000000
	L2Local 80_00050002_00020002-00_00000000_00000000					00C71	0000002B
	Station Descriptor:02340000, DestIndex:0239, RewriteIndex:F005
==========================================
	Egress:Asic 2, switch 1
	Output Packets:
------------------------------------------
	Packet 1
	Lookup		Key-Used			Index-Hit A-Data
	OutptACL 50_0D020202_0D010101-00_40000014_000A0000					01FFE	03000000
	Port	Vlan	SrcMac	DstMac	Cos	Dscpv
				Catalyst 3750-E and 3560-E Switch Software Configuration Guide
	OL-9775-02							45-23